Not much to add to excellent advice above from many owners n hardcore users. I have a phono 2se, 5SE and REF80S.
im at 9K happy hours on the 5SE
keep a tube log as noted the 2 - 2.5 K hour change interval on the 6550. You also have a. 6H 30 in the power supply to look after along w the 4x in gain stages.
i have the heavy version plastic covers and they Slightly deform…
im a bit of a black sheep prefer to run USA production Tung Sol black plates in the power supply - Andy at Vintage tube is likely the last source you can trust w that significant sonic upgrade. Also get 3X HRS Nimbus couplers. If you get a metal top get a damper block.
finally have fun

